1. Field of the Invention
The present invention generally relates to a telephone, in particular, the present invention relates to a call monitor function of a telephone.
2. Description of Prior Art
Since the invention of the telephone, it has become an indispensable communication means for communication in everyday life. A telephone plays a critical role in everyday life or work.
In an example of making internal calls within a company, switchboard systems were devised in the market for reducing the cost generated by calls among internal staff within a company and facilitate the management of internal telephones of the company. A switchboard system mainly comprises a private branch exchange (PBX) connected with several telephones (referred as extension telephones in the following). When an extension telephone dials out, the call request is sent to a switchboard via the private branch exchange, then the call request is dialed out via the switchboard. One advantage of using the switchboard systems is that the inter calls among each extension telephones are made via the private branch exchange instead of the switchboard; therefore charges paid to the telecom companies for these communications can be saved.
Further, a telephone for the switchboard systems generally has a plurality of Busy Lamp Field (BLF) keys on the housing, where light emitting diodes of the BLF keys flash upon pressing. The BLF keys are set to associate with corresponding specific extension telephones. Subscribers are informed of the current phone status via the BLF keys.
In addition, following setting the BLF key to associate with the corresponding extension telephone, the BLF key can be set as a hot key. Subscribers press the BLF key on the housing, the telephone then autodial out to the extension corresponding telephone and the time spent on dialing by a subscriber is saved.
However, the functions of the BLF keys are applicable to a plurality of extension telephones of the same switchboard system. If the extension telephone associate with a phone number is dialing out via switchboard, the BLF function is not applicable to the extension telephone. Subscribers using other extension telephones are not allowed to monitor the current phone status of the extension telephone. Thus, it is inconvenient and inefficient to subscribers in demand for frequent contacts with international branches and specific important clients, or subscribers having high call volume.
In view of this, it is desirable in the market to provide an innovative BLF monitor function, where telephones can monitor current status of telephones in different switchboard systems in addition to local telephones of the same switchboard system.